In recent decades, beauty salons providing nail and hair care services have cropped up on nearly every major street across the nation. California has experienced the largest expansion, mainly due to the growth of the nail care sector; the number of licensed nail technicians has grown nearly three-fold from 35,500 in 1987 to 114,000 in 2007. Vietnamese immigrant women comprise a large majority of the nail care sector. Hair and nail care workers routinely handle cosmetic products that contain a multitude of hazardous compounds, a number of which have been shown to cause reproductive abnormalities in animal studies. Since the vast majority of the workforce is composed of women in their childbearing age, there has been growing public concern for the reproductive health of workers in this industry. We propose to conduct a statewide population-based retrospective cohort study of cosmetologists (provides hair care services) and manicurists (provides nail care services) in California. Our hypothesis is that women working as cosmetologists and manicurists during pregnancy have a higher risk of adverse birth outcomes due to occupational exposures to exogenous compounds. Our specific aims are: Aim 1. Determine whether working as a cosmetologist or manicurist during pregnancy increases the risk of adverse neonatal health, including low birth weight, preterm delivery, small-for-gestational-age, perinatal death, and congenital malformations. Aim 2. Determine whether working as a cosmetologist or manicurist during pregnancy increases the risk of maternal perinatal risk factors, including preeclampsia, hypertension, and labor complications (e.g., prolonged/ precipitous labor, postpartum hemorrhage). This would be the largest, most racially-diverse study to date, capturing a cohort of licensed professionals that includes immigrant workers, to examine occupational links to adverse birth outcomes. In addition, the study would span the longest period of follow-up (1996-2008) for a reproductive outcomes study of this workforce, with nearly 50,000 births for workforce members. Using well-established probabilistic record- linkage between California's statewide cosmetology licensee and birth registry files, we will compare state- licensed cosmetologists and manicurists to two comparison groups: 1) the general population of women, and 2) women in other occupations that are not likely to be exposed to chemicals found in beauty salons (e.g., teachers, realtors, accountants, restaurant workers, receptionists, bank teller, and other office workers). Findings from the study can lead to etiologic research to better understand chemical links to reproductive health effects, which can ultimately inform future targeted interventions as well as chemical policy reforms. Thus, there is potential for high impact for both workers and consumers of cosmetic products.